Anxiety can be caused by numerous factors, ranging from external stimuli, emotional abandonment, shame, to experiencing an extreme reaction when first exposed to something potentially anxiety-provoking. Research has not yet explained why some people will experience a panic attack or develop a phobia, while others growing up in the same family and shared experiences do not. It is likely that anxiety disorders, like all mental illness, is caused by a complex combination of factors not yet fully understood. These factors likely include childhood development, genetics, neurobiology, psychological factors, personality development, and social and environmental cues.

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is the handbook used for diagnosis of mental health disorders, and is widely used by health care professionals around the world. For each disorder, the DSM has a description of symptoms and other criteria to diagnose the disorder. The DSM is important, because it allows different clinicians and/or researchers to use the same language when discussing mental health disorders. The first DSM was published in 1952 and has been updated several times after new research and knowledge became available. In 2013, the most recent version of the DSM, the DSM-5, was released. There are a few important differences with its predecessor DSM-IV regarding anxiety disorders. First, Obsessive Compulsive Disorder (OCD) is not part of the anxiety disorders any more, but now has its own category: Obsessive-Compulsive, Stereotypic and related disorders. Second, Post-Traumatic Stress Disorder (PTSD) now also has its own category: Trauma and Stressor-related Disorders.

People with panic disorder often worry about when the next attack will happen and actively try to prevent future attacks by avoiding places, situations, or behaviors they associate with panic attacks. Worry about panic attacks, and the effort spent trying to avoid attacks, cause significant problems in various areas of the person’s life, including the development of agoraphobia (see below).